[WIP/Proof] code preview button in QR

[saxamaphone69]

Okay, not actually working because I'm missing something, but figure it's a good starting point if someone else wants to pick it up.

The current issues are:

• trying to get prettyPrintOne to run on the #code-preview element. When you run it in console, it returns the prettified HTML
• I think it needs to strip the [code] and [/code] tags upon preview, as at this point they are included
• There probably needs to be some way to convert "hey [code]code[/code] this is [code]function() { cool; }[/code]" correctly (in that again, only the text within the code tags is rendered within the existing prettyprint and prettyprinted classes